Dockboard



I Jan. 24, 1967 D. P. DIETER ETAL DO'CKBOARD Filed Oct. 5, 1964 INVENTORS DONALD P. DIETED WILLIE O. QIGGS United States Patent 3,299,456 DOCKBOARD Donald P. Dieter, Chicago, Ill., and Willie O. Riggs, Springfield, Tenn, assignors to Unarco Industries, Inc., Chicago, 1th, a corporation of Illinois Filed Get. 5, 1964, Ser. No. 401,364 Claims. (Cl. 14-71) This invention relates to dockboards and more particularly to a safety stop means for limiting downward movement of a dockboard when it is at a level below the horizontal traffic position and is not supported in the normal manner by the lip thereon.

In the operation of dockboards provided with pivoted lips, the lip normally rests on a stop member on the frame when the board is in its horizontal cross tr-afiic position 'with the lip depending. If the board should be at an angle below its horizontal crosstrafiic position when a truck on which the lip is resting pulls away and the lip swings down the lip will not engage the stop to support the board and the board 'will consequently be free to move down to its maximum lowered position. Thus if a person walks on the board or should drive a truck over it the board would tend to swing down to the maximum possible extent thereby possibly injuring the person or damaging property.

It is accordingly one of the objects of the present invention to provide a dockboard in which safety support means are provided to limit downward movement of the board when it is not supported by the lip.

According to a feature of the invention, a pivoted strut element is provided on the frame to engage either with a smooth surface on a cam plate over which the strut element can slide freely so the board can move downwardly freely or the board can move downwardly freely or with one or more stop shoulders on -a latch plate to limit downward movement of the board. Control means are preferably provided to control each plate as it is engaged by the strut. In the preferred construction, the latch plate is slidable to expose or to conceal the stop shoulder or shoulders thereon and may be connected to the pivoted lip to be moved thereby as the lip moves between its depending and resting positions.

The above and other objects and features of theinvention will be more readily apparent from the following description when read in connection with the accompanying drawing, in which:

FIG. 1 is a side view with parts in section of a dockboard embodying the invention, parts being omitted for clarity;

FIG. 2 is a partial view similar to FIG. 1 showing the dockboard in its normal operating position; and

FIG. 3 is a view similar to FIG. 2 showing the dock board in a position in which the safety stop is functioning.

The dockboard, as shown in FIG. 1, comprises a frame, indicated generally at 10, which is adapted to be set in a recess in a loading dock. At one end, the frame includes upright members 11 to which the dockboard, indicated at 12, is pivoted. At its opposite end the frame carries a raised stop plate 13 which may have an upturned lip, as indicated at 14, at the forward edge thereof.

A lip 15 is hinged to the free end of the dockboard on a hinge 16 to swing from 21 depending position, as shown in FIGS. 1 and 3, to a raised position, as partly shown in FIG. 2, in which it forms in effect a continuation of the dockboard.

The dockboard is adapted to be raised by spring mechanism comprising one or more pivoted triangular plates 17 pivoted on the frame 18 and carrying rollers 19 which engage the lower surface of the dockboard. Spring-s 21 connected to the plate or plates tend to swing them in a tially level with the normal dock surface.

direction to raise the dockboard. Normally the dockboard is held in lowered position by any of a number of different forms of hold down mechanism, not shown, which can be released by the operator when it is desired to elevate the board. Preferably also means are provided to lift the lip 15 to its raised position as the board is raised. This means may take the form of any one of several known constructions and is omitted for simplicity of illustration.

When the dockboard is in its horizontal cross traflic po sition, as shown in FIG. 1, the lip 15 depends therefrom and engages the stop plate 13 behind the upturn-ed shoulder 14. In this position, the lip will hold the dockboard against further downward movement and will enable traflie to move across it since its upper surface is substan- In use the board may swing from an elevated position in which it angles upwardly to a lowered position below the level of the dock, as shown in FIGS. 2 and 3.

When the dockboard is being used with the lip extended, the lip will normally engage the bed of a truck in front of the dock to bridge the space between the dock and the truck bed. When the truck pulls away from the dock at the completion of a loading or unloading operation, the lip will swing downwardly to depend from the dockboard and when the dockboard is moved down to its cross tr-affic position the lip will engage the stop plate 13 and will support the board in the normal manner, as shown in FIG. 1.

On occasions, however, the truck may pull away from the dock when the board is below the horizontal position substantially as shown in FIG. 2. The stop means of the present invention will prevent the board from moving down further in the event this should occur.

As shown, the stop means includes a generally vertically extending strut 22 pivoted at its lower end on a horizontal axis 23 on the frame 10 and carrying a stop pin 24 at its upper end. A cam plate 25 terminating in a lower edge at an acute angle to the surface of the dockboard is secured to the undersurface of the dockboard in a position to be engaged by the pin 24. Preferably two plates 25 spaced slightly apart are provided slidably to receive between them a latch plate 26. The latch plate 26 is formed with one edge generally parallel to the sloping edge of the cam plate 25 and which is formed with one or more latching notches 27 adapted to receive the latch pin 24. The latch plate is adapted to slide parallel to the undersurface of the board 12 and its sliding movement .is guided and limited by a pin or bolt 28 carried by the plate or plates 25 and extending through an elongated slot 29 in the latch plate. A spring 31 connected to the latch plate and to one of the plates 25 normally urges the latch plate to the right, as seen in the drawings, so that the notches 27 therein will be exposed beyond the sloping edge of the plate 25. Thus the latch plate is normally in a position in which the pin 24 will engage in one or the other of the notches 27 to limit downward movement of the board without restricting upward movement thereof.

To make the latch plate inoperative so that board can be moved downward below the horizontal traffic position during use, the latch plate is adapted to be retracted to the position shown in FIG. 2 in which its notched edge lies within the sloping edge of the guide plate 25. For this purpose a portion of the hinge 16 which is connected to the lip 15 is provided with a projecting arm 32 whose free end is connected through a spring 33 to the latch plate. When the lip is in its depending position, as shown in FIGS. 1 and 3, the spring 33 is relaxed and the spring 31 will shift the latch plate to the right, as shown in FIG. 3. When the lip is raised as, for example, when the dockboard is in use the arm 32 will swing to the position shown in FIG. 2 to stretch the spring 33 which will overpower the spring 31 and shift the latch plate to the left so that its notched edges are concealed by the guide plate. In this position the dockboard can move freely to its maximum lowered position since the pin 24 will slide freely over the lower sloping edge or cam surface on the guide plate 25 so that the board can be used in the normal manner.

However, if a truck on which the lip is supported should pull away from the dock with the dock in a lowered position, as shown in FIGS. 2 and 3, the lip would swing down missing the stop plate 13, as illustrated in FIG. 3. At this time, however, the latch plate will be moved to the right by the spring 31 and the pin 24 will engage in the notch 27 immediately above it thereby to limit downward movement of the board below the position which it then occupies. Thus if a person should walk on the board while in this condition or should accidentally drive a truck on it the board would be permitted to move down a maximum of one or two inches only rather than to the full extent of its downward movement so that injury or damage would be minimized.

While one embodiment of the invention has been shown and described herein, it will be understood that it is illustrative only and not to be taken as a definition of the :scope of the invention, reference being had for this purpose to the appended claims.

What is claimed is:

1. A dockboard comprising a frame, a generally rectangular board pivoted at one end on the frame on a horizontal axis for swinging vertically, a lip pivoted on the free end of the board to swing from a depending position to a raised position forming an extension of the board, a strut pivoted on the frame and extending toward the underside of the board, a latch plate and a cam plate i carried by the board on its underside to be engaged by the free end of the strut, resilient means urging the free end of the strut into engagement with the latch and cam plates, the cam plate being formed with a smooth surface over which the free end of the strut can move to permit free vertical movement of the board, the latch plate being formed with at least one latching surface engageable with the free end of the strut to limit downward movement of the board, the plates being movable relative to each other, and control means operable in conjunction with movement of the lip to move the plates relative to each other thereby to position the plates so that the strut will engage the cam plate when the lip is raised and the latch plate when the lip is in its depending position.

2. A dockboard comprising a frame, a generally rectangular board pivoted at one end on the frame on a horizontal axis for swinging vertically, a lip pivoted on the free end of the board to swing from a depending position to a raised position forming an extension of the board, a strut pivoted on the frame and extending toward the underside of the board, a latch plate and a cam plate carried by the board on its underside to be engaged by the free end of the strut, resilient means urging the free end of the strut into engagement with the latch and cam plates, the cam plate being formed with a smooth surface over which the free end of the strut can move to permit free vertical movement of the board, the latch plate being formed with at least one latching surface engageable with the free end of the strut to limit downward movement of the board, the plates being mounted in side by side relationship and one of them being mounted for sliding movement relative to the other so that the edge portion of either plate may be exposed for engagement with the strut, and conil trol means operable in conjunction with movement of the lip to move the plates relative to each other, thereby to position the plates so that the strut will engage the cam plate when the lip is raised and the latch plate when the lip is in its depending position.

3. A dockboard comprising a frame, a generally rectangular board pivoted at its rear edge on the frame on a horizontal axis, a lip pivoted on the front edge of the board for swinging from a depending position to a raised position forming an extension of the board, a strut pivoted on the frame at its lower end on a horizontal axis to swing from a vertical upright position to an inclined position, a spring urging the strut to its upright position, a cam plate and a latch plate carried by the board in side by side relationship in planes normal to the pivotal axis of the strut and having generally parallel edges lying at an acute angle to the board and which are engageable with the upper end of the strut, the edge of the cam plate being a smooth surface over which the upper end of the strut can slide freely and the edge of the latch plate being formed with at least one projecting shoulder to engage the upper end of the strut and limit downward movement of the board, one of the plates being slidable parallel to the other whereby one or the other of the inclined edges of the plates projects to be engaged by the upper end of the strut, and control means operable in conjunction with movement of the lip to move the plates relative to each other, thereby to position the plates so that the strut will engage the cam plate when the lip is raised and the latch plate when the lip is in its depending position.

4. A dockboard comprising a frame, a generally rectangular board pivoted at its rear edge on the frame on a horizontal axis, a lip pivoted on the front edge of the board for swinging from a. depending position to a raised position forming an extension of the board, a strut pivoted on the frame at its lower end on ahorizontal axis to swing from a vertical upright position to an inclined position, a spring urging the strut to its upright position, a cam plate and a latch plate carried by the board in side by side relationship in planes normal to the pivotal axis of the strut and having generally parallel edges lying at an acute angle to the board and which are engageable with the upper end of the strut, the edge of the cam plate being a smooth surface over which the upper end of the strut can slide freely and the edge of the latch plate being formed with at least one projecting shoulder to engage the upper end of the strut and limit downward movement of the board, the latch plate being slidable relative to the cam plate so that the shoulder thereon may be retracted behind or projected beyond the inclined edge of the cam plate, and control means operable in conjunction with movement of the lip to move the plates relative to each other, thereby to position the plates so that the strut will engage the cam plate when the lip is raised and the latch plate when the lip is in its depending position.

5. The dockboard of claim 4 in which the control means includes a spring connected to the latch plate to urge it to a position in which the shoulder projects and a connection from the lip to the latch plate to move it to a position in which the shoulder is retracted when the lip is moved to its raised position.

References (Jilted by the Examiner UNITED STATES PATENTS 3,137,017 6/1964 Pfleger et al. 14-71 JACOB L. NACKENOFF, Primary Examiner. 

1. A DOCKBOARD COMPRISING A FRAME, A GENERALLY RECTANGULAR BOARD PIVOTED AT ONE END ON THE FRAME ON A HORIZONTAL AXIS FOR SWINGING VERTICALLY, A LIP PIVOTED ON THE FREE END OF THE BOARD TO SWING FROM A DEPENDING POSITION TO A RAISED POSITION FORMING AN EXTENSION OF THE BOARD, A STRUT PIVOTED ON THE FRAME AND EXTENDING TOWARD THE UNDERSIDE OF THE BOARD, A LATCH PLATE AND A CAM PLATE CARRIED BY THE BOARD ON ITS UNDERSIDE TO BE ENGAGED BY THE FREE END OF THE STRUT, RESILIENT MEANS URGING THE FREE END OF THE STRUT INTO ENGAGEMENT WITH THE LATCH AND CAM PLATES, THE CAM PLATE BEING FORMED WITH A SMOOTH SURFACE OVER WHICH THE FREE END OF THE STRUT CAN MOVE TO PERMIT FREE VERTICAL MOVEMENT OF THE BOARD, THE LATCH PLATE BEING FORMED WITH AT LEAST ONE LATCHING SURFACE ENGAGEABLE WITH THE FREE END OF THE STRUT TO LIMIT DOWNWARD MOVEMENT OF THE BOARD, THE PLATES BEING MOVABLE RELATIVE TO EACH OTHER, AND CONTROL MEANS OPERABLE IN CONJUNCTION WITH MOVEMENT OF THE LIP TO MOVE THE PLATES RELATIVE TO EACH OTHER THEREBY TO POSITION THE PLATES SO THAT THE STRUT WILL ENGAGE THE CAM PLATE WHEN THE LIP IS RAISED AND THE LATCH PLATE WHEN THE LIP IS IN ITS DEPENDING POSITION. 